Beware of what "looks" like a Graflok back. The Graflok has a focus panel that, while removeable, allows the film holder to slide under it, just like a spring back. It has a chrome tension arm on each side of the panel. The other is the Graflex back. Not the same thing at all. It has slider(s) on it, similar to the Graflok, but the focus panel must be removed to install the film holder which is held in place by the slider(s). Regular Graphic type film holders will NOT fit the Graflex back. It uses only (marked) "Graflex" holders with grooves in the sides. The two backs can be hard to distinguish in pictures. Then, there is the old standby, the spring back. These cameras are often modified with the different backs to suit the needs of the user.

If memory serves, the "Super D" was made only in 4x5 and 3¼X4¼ models. Both were "super" because they incorporated a cable to trip a spring-loaded semiautomatic diaphragm when the shutter release was pressed. The lens is fitted to a square board, so it's much easier to interchange than (say) the lens on a "Series B," which screwed into a flange on the front.

The 4x5 model was supplied with a 190mm. f:5.6 "Ektar"; the 3¼x4¼, with a 152mm. f:4.5 "Ektar." I never saw the semi-auto diaphragm on any lenses other than those two.

Both sizes were available with the old standard "Graflex" back, which had a single retainer slide at the top, a flange at the bottom, and a light trap consisting of a lip at the right side of the back that mated with a groove on the "Graflex" accessories. This light trap served to hold the accessory in place.

The "Graflex" back was not designed to accept a spring-loaded focusing panel, unlike the later "Graflok." All the accessories, including an optional focusing panel (useful for adjusting the reflex focusing screen) clipped into the back in the same way.

I have heard that the newer "Graflok" back also was available, but I don't know whether it was offered for both models.

The 4x5 was discontinued earlier than the 3¼x4¼, perhaps because Graflex felt the latter more suitable for rollfilm, which was finding increased favor during the late '50s. For reasons I never have been able to fathom, Graflex never followed that perception far enough to develop a 2¼x3¼ model (logically, such a design would have a 135mm. lens, like the "R.B. Series B," with an auto diaphragm.

A used 4x5 "Super D" commands a premium price, because sheetfilm still is readily available for it, as are Polaroid backs. The 3¼x4¼ model is less pricey, and there has been a very modest revival of that sheetfilm format over the past couple of years. My guess is that the "Graflok" back would add to the value, and thus to the price.

In my recollection, most people who used the big reflexes in the '50s tended to use them with filmpack, which was compact, fast and convenient. Alas, it is no longer available.